A refracting telescope has an objective lens of focal length 80 cm, a diameter of 10 cm, and an eyepiece of focal length 5 cm and diameter 1 cm. What is the magnifying power of this telescope?

Question

Quizplus · Accepted Answer

The magnifying power of a telescope is given by:
$$M=\frac{f_{	ext{objective}}}{f_{	ext{eyepiece}}}$$
where $f_{	ext{objective}}$ is the focal length of the objective lens and $f_{	ext{eyepiece}}$ is the focal length of the eyepiece. Plugging in the values given,
$$M=\frac{80	ext{ cm}}{5	ext{ cm}}=16$$
Therefore, the magnifying power of the telescope is 16×.

A Refracting Telescope Has an Objective Lens of Focal Length